Use of sulfated glycosaminoglycans for establishing effective labor in women

ABSTRACT

The invention refers to the use of sulfated glycosaminoglycans having an anticoagulant activity of 100 BP units/mg or less for the manufacture of a pharmaceutical preparation for prophylactic priming or curative treatment of the cervix and the myometrium for establishing effective labor in women.

This application is a Continuation of U.S. application Ser. No.10/500,284 filed on Jul. 1, 2004 now U.S. Pat. No. 7,407,945 which isthe national phase of PCT International Application No. PCT/SE03/00004filed on Jan. 2, 2003, which designated the United States, and on whichpriority is claimed under 35 U.S.C. §120. This application also claimspriority under 35 U.S.C. §119(a) on Patent Application No(s). 0200005-7filed in Sweden on Jan. 2, 2002. The entire contents of each of theabove documents is hereby incorporated by reference.

The present invention refers to the use of certain sulfatedglycosaminoglycans for the manufacture of a pharmaceutical compositionfor the prevention and treatment of slow progress of term labor.

BACKGROUND

A common clinical problem in obstetrics is prolonged or in some waydysfunctional labor. Slow progress or arrest of labor is documented inabout 40-60% of all parturitions in Sweden. In developing countriesmaternal deaths due to labor arrest with heavy post partum bleedings arethe most common reasons for maternal deaths. Slow progress of labor isthe most common indication for emergency caesarian section, which inturn often results in a demand for elective caesarian section at thenext pregnancy. Other complications of protracted labor generateincreased fetal asphyxia resulting in long-term sequele.

The uterus is composed of two parts, the corpus and the cervix havingdifferent functions during pregnancy and parturition. The corpus utericonsist predominantly of smooth muscle bundles, the myometrium, embeddedin extra cellular matrix, ECM, and the cervix consists mainly of ECM.The dominating components of the ECM are the collagens, but there arealso proteoglycans albeit in a smaller quantity. Proteoglycans consistof a protein core to which one to a hundred polysaccharide chains, theglycosaminoglycans, are attached.

The coordination between the uterine contractions and the softening, orin other words ripening, and dilation of the cervix is crucial for anormal parturition. Incongruity between these processes leads toabnormal parturitions.

During pregnancy and labor both the cervix and the corpus are remodeled.A profound remodeling of the corpus results in an approximatelyseven-fold increase in volume. An insufficient uterine remodeling isrelated to a disturbed contractility. A normal dilation of the cervixopening from 1 to 10 cm during established labor implies a totalreconstruction of the cervical connective tissue generated through adecrease of the concentration of collagen and proteoglycans andresulting in a soft and elastic cervix. Disturbances in the cervicalripening can, if the process starts too early, result in a pre-termdelivery. Pre-term labor must be coordinated with a pre-term cervicalripening in order to give a premature delivery. On the other handinsufficient cervical ripening results in post-term pregnancy with highfrequency of protracted labor and instrumental deliveries. Thus thecervical ripening and myometrial contractions are two processes, whichmust be coordinated to accomplish a normal delivery.

The physiology of both normal and protracted labor is still obscure. Thehormonal control seems to include an inhibitory effect by progesteroneand activation by increasing estrogen levels. Corticotrophin releasinghormone, prostaglandin and a changed estrogen/progesterone ratio hasbeen suggested to be involved in the initiation of labor. Intravenousinfusion of oxytocin, introduced in 1950, is still the dominatingtreatment of protracted labor and recently published investigations andreview articles on slow progress of labor mainly present differenttreatment schedules of oxytocin administration. This treatment fails inmany cases and results in an increasing number of operative deliveries.There have been few efforts to develop new drugs for labor augmentationdespite a tremendous global problem of slow progress of labor.

Induction of labor in women with unfavorable cervices has been performedby local application of prostaglandin E2 for about twenty years. In15-20% of said cases cervical ripening and labor induction fail. Mostprominent is arrest of labor.

PRIOR ART

Uterine contractions due to heparin are described as a side effect ofintravenous administration of high-dose of heparin for the treatment ofvein thrombosis to a 32 year old multigravida in the thirty-second weekof pregnancy, by K. Shaker et al., British Medical Journal 16 Nov. 1974.Heparin is a glycosaminoglycan isolated on a commercial basis fromanimal tissues and used in the clinic as an antithrombotic drug.

EP 0 509 120 B1 discloses the use of glycosaminoglycans, GAGs, for thepreparation of a topical pharmaceutical composition for the preventionand therapy of diseases of the cervical vaginal area. As examples ofsaid diseases are mentioned dystrophy and atrophy states induced by lackof estrogen hormones, vaginal dermatitis, a specific vaginitis etc. TheGAGs are said to take part in the safeguarding and restoring of thenatural vaginal ecosystem.

The glycosaminoglycans are described as belonging to a highlyheterogeneous class of macromolecules having very long moleculescontaining repeating disaccharide units forming linear macromolecules.In general each of the repeating units comprises a residue consisting ofan aminosugar, that is glucosamine or galactosamine, and a uronic acidresidue consisting of glucuronic acid or iduronic acid. The hydroxylgroup at C₂, C₃, C₄ and C₆ and the amino group on C₂ may be substitutedby sulfate groups. The GAGs are represented by the following compounds:heparin, heparan sulfate, dermatan sulfate, hyaluronic acid, chondroitinsulfate, keratan sulfate.

EP 0 867 452 A1 refers to a cervical ripening agent which as an activeingredient contains hyaluronic acid or a derivative thereof.

It is well known that glycosaminoglycans have a multitude of effects oncell activity.

DESCRIPTION OF THE INVENTION

It has recently been found that the expression of heparan sulfateproteoglycans varies during the uterine remodeling during pregnancy andlabor. They are thus believed to play a pivotal role in labor. It hasalso been found that treatment of human uterine strips with sulfatedglycosaminoglycans enhances the contractile activity thereof.

The present invention refers to the use of sulfated glycosaminoglycanshaving an anticoagulant activity of 100 BP units/mg or less for themanufacture of a pharmaceutical preparation for prophylactic priming orcurative treatment of the cervix and the myometrium for establishingeffective labor in women. Normal labor includes a softening of thecervix and regular myometrial contractions.

The anticoagulation effect was evaluated by measuring the increase inclotting time per mg sulfated glycosaminoglycan, and is stated in BPunits per mg. Heparin has an anticoagulant activity of 157 BP units/mg.

The sulfated glycosaminoglycans, that is mainly heparin, heparansulfate, dermatan sulfate and chondroitin sulfate, are composed ofalternating hexosamine and uronic acid residues. Hyaluronic acid has nosulfate groups. The presence of D-glucuronic acid (GlcA) and its C-5epimer L-iduronic acid (IdoA) and the specific sulfation of hexosaminesand uronosyl residues endow the polymer an extreme structural variation.The structure can range from none or very few to nearly 100% iduronicacid-containing disaccharides. The organization of GlcA- andIdoA-N-hexosamine containing disaccharides can vary from long blocks toan alternating disaccharide pattern. A high degree of sulfation and ahigh degree of iduronic acid sulfate generally involves a highbiological activity of the compound. There are different well-definedpolysaccharides of dermatan sulfate (DS), chondroitin sulfate (CS),heparan sulfate (HS) and depolymerised heparin.

Heparan sulfate, having glucosamine and uronic acid as repeatingdisaccharides and consisting of N-acetylated and N-sulfateddisaccharides that are arranged mainly in a segregated manner, hasubiquitous distribution on cell surfaces and in the extracellularmatrix. It is generally less sulfated and has a lower iduronate contentthan heparin and has a more varied structure. Interactions betweenheparan sulfate and proteins are implicated in a variety ofphysiological processes, such as cell adhesion, enzyme regulation,cytokine action, virus entry and anticoagulant properties. Heparansulfates possess anticoagulant activity depending on the presence of aspecific anticoagulant pentasaccharide, however considerably less thanheparin. Heparan sulfate is a linear polysaccharide which can beprepared from porcine intestinal mucosa or from bovine lung, fromheparin side fractions using cetylpyridinium chloride fractions andsequential salt extraction as described by Fransson et al., Structuralstudies on heparan sulphates, Eur. J. Biochem. 106, 59-69 (1980).

The invention refers to the use of a sulfated glycosaminoglycan, whichbelongs to the group consisting of heparan sulfates and depolymerisedheparan sulfates.

Chondroitin sulfate is a sulfated linear polysaccharide consisting ofalternating glucuronic acid and N-acetyl-galactosamine residues, thelatter being sulfated in either 4 or 6 position. They can be preparedfrom bovine tracheal or nasal cartilage. CS is of importance for theorganization of extracellular matrix, generating a interstitial swellingpressure and participating in recruitment of neutrophils.

The invention also refers to the use of chondroitin sulfates ordepolymerised chondroitin sulfates.

Dermatan sulfate is a sulfated linear polysaccharide consisting ofalternating uronic acid and N-acetylated galactosamine residues. Theuronic acids are either D-GlcA or L-IdoA and the disaccharide can besulfated in 4 and 6 and 2 on galactosamine and IdoA, respectively. DScan be prepared from porcine skin and intestinal mucosa. Dermatansulfate possesses biological activities such as organization ofextracellular matrix, interactions with cytokines, anticoagulantactivities and recruitment of neutrophils.

The invention also refers to the use of dermatan sulfates ordepolymerised dermatan sulfates.

Low molecular weight heparins or depolymerised heparins are linearoligosaccharides having a M_(r) of between 2 and 10 kDa, mainlyconsisting of alternating N-sulfated glucosamine and IdoA residues andoften containing the anticoagulant pentasaccharide. They can be preparedfrom heparins by specific chemical cleavage. Their main clinicalfunction is to inhibit factor Xa, resulting in an antithrombotic effect.It is proposed to have antimetastatic properties. Fragmin® (Pharmacia,Sweden) is an example of a low molecular heparin obtained by controlleddepolymerisation of heparin and having an antithrombotic effect owing toinhibition of factor Xa. Heparin fragments having selectiveanticoagulant activity, as well as methods for the preparation thereof,are described in U.S. Pat. No. 4,303,651. The anticoagulant effect is,however, normally not desirable for a preparation to be used duringlabor.

The invention especially refers to the use of a glycosaminoglycan whichbelongs to the group consisting of depolymerised heparins having arelative molecular weight below 10000 Da, preferably not higher than6000 Da.

It is essential that the anticoagulant activity is not too high, andaccording to a preferred aspect the invention refers to the use of asulfated glycosaminoglycan having an anticoagulant activity of 30 BPunits/mg or less.

Tests in vitro suggest that low sulfated structures of low or noanticoagulative potency are preferred compounds. Thus side productsobtained during manufacture of heparin are good candidates for selectionof starting material. Compounds with the desired properties can beobtained from heparan and heparin side fractions using specificperiodate oxidation to eradicate the antithrombin III bindingproperties.

Selective N-desulfation followed by re-N-acetylation, or selectiveO-desulfation also yields compounds with low anticoagulant activity.

Selective N-deacetylation followed by specific N- and/or O-sulfationalso yields compounds of desired activity.

The invention especially refers to the use of a glycosaminoglycan havinga sulfate/hexosamine ratio below 1.0 and an anticoagulant activity, orclotting time, less than 10 BP units/mg.

If the amount of endogenous oxytocin has reached its optimal level atthe time for onset of labor, a pretreatment with the sulfatedglycosaminoglycans to be used according to the invention will initiatethe onset of labor. In case of an insufficient endogenous oxytocinlevel, the sulfated glycosaminoglycans can be used in a single dose incombination with i.v. oxytocin for the priming of the myometrium.

The invention also refers to the use of sulfated glycosaminoglycans forthe manufacture of a pharmaceutical preparation which can beadministered locally that is topically, such as by intracervical,vaginal, rectal, or dermal administration, or systemically that isparenteral, such as by subcutaneous or intravenous injection. Thepharmaceutical composition can also be given by oral administration.

For parenteral administration the active compounds can be incorporatedinto a solution or suspension, which also contain one or more adjuvantssuch as sterile diluents such as water for injection, saline, fixedoils, polyethylene glycol, glycerol, propylene glycol or other syntheticsolvents, antibacterial agents, antioxidants, chelating agents, buffersand agents for adjusting the tonicity. The parenteral preparation can bedelivered in ampoules, disposable syringes or as infusions.

A topical preparation consists of the active sulfated glycosaminoglycansin combination with a conventional pharmaceutically acceptable carrier.The carrier or excipient can be a solid, semisolid or liquid materialthat can serve as a vehicle for the active substance. Examples oftopical preparations are an ointment, cream, gel, nasal or vaginalspray, lotion, solution or suspension.

In order to bring about an effective labor the sulfatedglycosaminoglycans can be administered in a single dose every 24 h for aperiod of 1-30, preferably 1-10 days. The dose must be estimated as thelowest dose giving myometrial contractions. An estimated single dose is25-100 mg/d, but may be up to 1 g or more. The dose is related to theform of administration.

EXAMPLES Example 1 Preparation of Heparan Sulfates

10 g of the heparin by-product, TB 001-91 SVCM 950130 (Kabi-Pharmacia,Sweden) was dissolved in 1 l of 5% calcium acetate—0.5 M acetic acid.The solution was filtered. The filtered solution was then adjusted to anethanol concentration of 18%. The supernatant after centrifugation wasthen adjusted to an ethanol concentration of 36%. The precipitate wascollected by centrifugation. The following heparan sulfates wereprepared in accordance with Fransson et al., Structural studies onheparan sulphates, Eur. J. Biochem. 106, 59-69 (1980.

Preparation of HS6

The precipitate obtained between 18 and 36% ethanol was dissolved in 1.2M of NaCl. 18 g of cetylpyridinium chloride, CPC, was added and aprecipitate was allowed to develop for 24 h. The precipitate wasrecovered by filtration and redissolved in 2 M NaCl. The filtrate wasused for the preparation of HS5. To the resolved precipitate 3 volumesof ethanol was added. The resulting precipitate was allowed to developfor 16 h and the collected by centrifugation. Finally it was redissolvedin water and reprecipitated with 3 volumes of ethanol—0.4% of sodiumacetate. The precipitate was collected by centrifugation and dried. Theyield was 4.34 g.

Preparation HS5

The filtrate from the preparation of HS6 was then diluted with 0.1% CPCto a final concentration of 1.0 M NaCl. It was then treated as in HS6.The filtrate was used for the preparation of HS4. The yield was 0.82 g.

Preparation of HS4

The filtrate from the preparation of HS5 was then diluted with 0.1% CPCto a final concentration of 0.8 M NaCl. It was then treated as in HS6.The filtrate was used for the preparation of HS3. The yield was 0.51 g.

Preparation of HS3

The filtrate from the preparation of HS4 was then diluted with 0.1% CPCto a final concentration of 0.6 M NaCl. It was then treated as in HS6.The filtrate was used for the preparation of HS2. The yield was 0.17 g.

Preparation of HS2

The filtrate from the preparation of HS3 was then diluted with 0.1% CPCto a final concentration of 0.4 M NaCl. It was then treated as in HS6.The yield was 0.09 g.

The different heparan sulfates were analysed as to the content ofglucuronic acid, iduronic acid, and total sulfate groups. The number ofsulfate groups on the amino group of the hexosamine was determined asmole per mole, and the percentage of iduronic acid residues wasdetermined. The results are given in Table 1 below. The anticoagulantactivity was also evaluated by measuring the clotting time per mgheparin sulfate, and stated in BP units per mg in Table 1 below.

TABLE 1 Analysis of heparan sulfates Sulfate/ N-sulfate/ IdoA-SO₄/Antico- hexos- hexos- total agulant amine amine IdoA/total uronicactivity Prepa- (mole/ (mole/ uronic acid acid (BP ration mole) mole)(%) (%) units/mg) HS2 0.56 0.26 30 10 — HS3 1.00 0.40 35 20 8 HS4 1.150.47 40 25 30 HS5 1.23 0.62 50 45 88 HS6 1.63 0.73 65 60 140

The anticoagulant activity of all the heparan sulfate preparations abovecan be abrogated by selective periodate oxidation, see Fransson L A, andLewis W. Relationship between anticoagulant activity of heparin andsusceptibility to periodate oxidation, FEBS Lett. 1979, 97:119-23.

Example 2 Preparation of Dermatan Sulfate

One kg of dried pig skin was suspended in 5 l of 0.5 M of NaCl, 0.01 MEDTA and 0.01 M of cysteine hydrochloride, pH 6.5. 500 mg of crystallinepapain was added and the digestion was allowed to proceed for 50 h. Thedigest was filtered and then precipitated with 75 ml of a 10% solutionof CPC. The resulting pyridinium complex was collected by filtration andthe redissolved in 2M NaCl containing 15% of ethanol. This solution wasdiluted with 3 volumes of 0.5% CPC. The precipitate was collected anddissolved in 200 ml 1 M of NaCl and 40 ml of ethanol. The material wasredissolved in 100 ml of water and then precipitated with 3 volumes ofethanol—0.4% sodium acetate. The resulting precipitate was collected anddried. The final yield was 2.32 g. See Fransson et al., Structure of pigskin dermatan sulfate. 1. Distribution of D-glucuronic acid residues.(1971) Eur. J. Biochem. 18, 422-430.

Preparation of Ds with Different Content of L-Iduronic Acid

2.2 g of the material obtained above was dissolved in 220 ml of 5%calcium acetate—0.5 M acetic acid. This solution was mixed with ethanoland the precipitates formed between 0-18% ethanol (DS-18), 18-36%ethanol (DS-36), and 36-50% ethanol (DS-50), respectively, werecollected. The materials were redissolved in water and reprecipitatedwith 3 volumes of ethanol—0.4% sodium acetate. After drying the finalyield was 0.9 g for DS-18; 1.02 g for DS-36; 0.28 g for DS-50.

The different dermatan sulfates were analyzed as to content of sulfategroups, glucuronic acid, iduronic acid and hexosamine, and the resultsare presented in Table 2 below.

TABLE 2 Analysis of dermatan sulfates Sulfate/hexos- IdoA/totalIdoA-SO₄/ amines uronic acid total uronic Preparation (mole/mole) (%)acid (%) DS-18 1.16 90 20 DS-36 1.12 75 15 DS-50 1.06 50 10

The DS preparations contain 99% galactosamine of total hexosamin and theHS and heparin preparations contain >97% glucosamine of totalhexosamine.

Experimental Test 1 Contractile Assay

In the following test heparan sulfate HS2 and HS6 obtained from theheparin side fraction TB 001-91 SVCM 950130 (Kabi-Pharmacia, Sweden)were tested. HS6 differs from HS2 by being more highly sulfated andhaving more L-iduronic acid residues (see Table 1 above).

Uterine samples were obtained from women undergoing elective caesariansection at 38-39 weeks of gestation. The samples measured 20×10×10 mmand were taken from the upper part of the isthmic incision. The biopsywas immediately placed in ice-cold Krebs-Ringer buffer. The biopsieswere cut into longitudinal strips, length 10-15 mm and breadth about 5mm. The strip was mounted vertically in an organ bath of 37° C.containing 2 ml Krebs-Ringer solution. The solution was bubbled with amixture of 95% O₂ and 5% CO₂ in order to maintain a pH in the bath of7.35-7.45. Experiments were carried out after the strips hadequilibrated to a stable contractile state, usually within 1-2 h aftermounting. The contractions were recorded isometrically with a Grassmodel 7 polygraph (Grass Instr. Co., Quincy, Mass., USA). All sampleswere exposed to 100 mM KCl during the experiment in order to get astandardized maximum response. Different doses of heparan sulfate werethen added to the bath containing the uterine strip. After 20 min 1 Uoxytocin was added. Addition of 1 U oxytocin only was used as a control.

This procedure was repeated using 6 μg of heparan sulfate. After 20 min1 unit of oxytocin was added. The contractions were recorded andevaluated by integrating the surface under the curve. Two heparansulfates, HS2 and HS6, with different structure was added and as control1 unit of oxytocin was used. See Table 3 below.

TABLE 3 Relative contractility of myometrial strip after stimulationwith heparan sulfate and oxytocin, in % of unstimulated controlUnstimulated Oxytocin HS and control control, 1 U HS oxytocin HS2 100226 289 936 HS6 100 226 183 584The combination of oxytocin and HS6 resulted in a 2.5 fold increase ofcontractile force and the combination with HS2 gave a 4.1 fold increasein contractile force.

This shows that heparan sulfate enhances the contractile force of humanuterine strips in vitro. The effect is dependent on the heparan sulfatestructure, and a low sulfated structure appears to be more effective.

When this test was repeated with dermatan sulfate, DS-18, see Table 2,contractility was registered, but the results have not yet beenevaluated.

Test 2 Effect on Ca²⁺ Levels in Cervical Fibroblasts

Fibroblast cultures were established from non-pregnant, and termpregnant patients and from women delivered vaginally (after partuspatients). The cells were cultured in monolayer cultures with minimumessential medium with 10% donor calf serum. For experiments these cellswere plated on cover glasses with at semi-confluence and loaded withFluo-4 in phosphate buffered saline containing 10 mM HEPES for 30 min.Initially phosphate buffered saline containing 10 mM HEPES(HEPES-buffer) was pumped into the observation chamber for 30 s, thenKCl in the same buffer was pumped for 60 s followed by HEPES-buffer for30 s. Then 10 ng of PDGF/ml in HEPES-buffer was added. The fluorescencewas monitored continuously for 3 min. In other experiments PDGF wasreplaced with 100 μg of HS6. No change of fluorescence was noted incultures established from non-pregnant and term pregnant patients. Incultures obtained from patients directly after partus KCl, PDGF and HS6all induced a transient 4-8 fold increase of fluorescence, whichdemonstrates a transient increase of intracellular Ca²⁺. Thisdemonstrates that cells in cultures established from patients afterpartus are activated by HS6. This effect is postulated to be ofimportance at partus for final preparation of cervix for delivery.

Test 3 Clinical Test With Dalteparin Sodium Salt (FragMin®)

Clinical data on delivery outcome in nulliparous women have beenstudied. 14 nulliparous women were given Fragmin® (Pharmacia, Sweden)subcutaneous during pregnancy due to an increased risk of thrombosis.The administered prophylactic dose was 5000 IE daily in all but 4 womenwho had 2500 IE daily. Eight of the women were treated more than 12weeks (range 12-28 weeks) and 6 of them during 1-6 weeks. As matchedcontrols served the next 13 nulliparous women without Fragmin®medication giving birth in the same clinic immediately after the womenincluded in the study. Endpoints were labor-delivery time (hour) andnumber of caesarian sections and their indications.

No correlation could be found between the duration of the treatment andthe duration of the parturition. The labor—delivery time turned out tobe 5.8±2.6 h in the patient group and 14.0±6.3 h in the control group(p<0.001). Furthermore slow progress of labor was reported in 6 out of13 subjects in the control group compared to 1 of 14 in the treatmentgroup.

The number of caesarian sections was 3 in each group, but theindications in the study group were pre-ecklampsia, insufficientanalgesia and suspected fetal asphyxia. In the control group all 3 hadthe main indication arrest of labor, in two women in combination withsuspected fetal asphyxia.

The labor-delivery time has also been investigated in 21 parous womenwhich had been given Fragmin® as above in comparison to 9 controls. Thelabor-delivery time in the group given Fragmin® was 3.5±2.9 h (range0.5-8) compared to 5.9±2.1 h (range 3-12) in the control group (p<0.05).The labor-delivery time was thus significantly lower in the medicatedgroup.

1. A method for priming or treating the cervix and the myometrium forestablishing effective labor in a woman, comprising the step of:administering to a pregnant woman for a period of 1 to 30 days aneffective amount of at least one sulfated glycosaminoglycan selectedfrom the group consisting of heparan sulfate, depolymerised heparansulfate, dermatan sulfate, depolymerised dermatan sulfate, low molecularweight heparin and depolymerised heparin, said at least one sulfatedglycosaminoglycan having an anticoagulant activity of 100 BP units/mg orless, wherein the effective amount is sufficient to increasecontractility of the pregnant woman's myometrium and/or increasecervical ripening, wherein the pregnant woman does not suffer anycomplication requiring antithrombotic therapy with sulfatedglycosaminoglycans.
 2. The method according to claim 1, wherein the atleast one glycosaminoglycan comprises at least one glycosaminoglycanselected from the group consisting of heparan sulfate and depolymerisedheparan sulfate.
 3. The method according to claim 1, wherein the atleast one glycosaminoglycan comprises at least one glycosaminoglycanselected from the group consisting of dermatan sulfate and depolymeriseddermatan sulfate.
 4. The method according to claim 1, wherein the atleast one glycosaminoglycan comprises depolymerised heparin having anaverage molecular weight below 10 000 Da.
 5. The method according to anyone of claim 1, 2, 3, or 4, wherein the at least one glycosaminoglycanhas an anticoagulant activity of 30 BP units/mg or less.
 6. The methodaccording to claim 1, wherein the at least one glycosaminoglycan has asulfate/hexosamine ratio below 1.0 and an anticoagulant activity of 10BP units/mg or less.
 7. The method according to claim 1, wherein the atleast one glycosaminoglycan is administered in combination withoxytocin.
 8. The method according to claim 1, wherein the at least oneglycosaminoglycan is administered topically in a topical pharmaceuticalpreparation.
 9. The method according to claim 1, wherein the at leastone glycosaminoglycan is administered in a parenteral pharmaceuticalpreparation.
 10. The method according to claim 4, wherein the at leastone glycosaminoglycan comprises depolymerised heparin having a molecularweight not higher than 6,000 Da.
 11. The method according to claim 1,wherein the complication requiring antithrombotic therapy is veinthrombosis or preeclampsia.
 12. The method according to claim 1, whereinthe effective amount is sufficient to increase contractility of thepregnant woman's myometrium and increase cervical ripening.